diff --git a/.github/workflows/reftest.yml b/.github/workflows/reftest.yml
index fc204e5728cb..c80516db49aa 100644
--- a/.github/workflows/reftest.yml
+++ b/.github/workflows/reftest.yml
@@ -7,10 +7,16 @@ jobs:
   ref-print:
     runs-on: ubuntu-latest
     steps:
-    - name: github.base_ref
-      run: echo github.base_ref=${{ github.base_ref }}
-    - name: github.merge_group.base_ref
-      run: echo github.event.merge_group.base_ref=${{ github.event.merge_group.base_ref }}
+    - name: set CI_BASE_BRANCH
+      run: |
+          if [ -n "${{ github.base_ref }}" ]; then
+              echo "CI_BASE_BRANCH=${{ github.base_ref }}" >> $GITHUB_ENV
+          elif [ -n "${{ github.event.merge_group.base_ref }}" ]; then
+              echo "CI_BASE_BRANCH=${{ github.event.merge_group.base_ref }}" | sed s.=refs/heads/.=. >> $GITHUB_ENV
+          fi
+
+    - name: echo CI_BASE_BRANCH
+      run: echo CI_BASE_BRANCH=$CI_BASE_BRANCH
     - name: fail-if
       if: github.event_name == 'merge_group'
       run: "false"